LIBRARY

nIPTERA 757
I11ented; hypopygiuI11 prominent. Eggs elongate-oval or somewhat spindleshaped;
dark; floating singly or in small or large rafts on the surface of the water.
Larvre or "phantoms" are elongate, subcylindrical; largest anteriorly and
pointed posteriorly; composed of prominent head and 12 body segments; transparent;
smooth with few small tufts of hairs on the body,large anal brush; four
exserted, elongated, fleshy blood gills and numerous hairs or bristles around
FIG. 271. The Clear Lake gnat. CllaoboTUS astietopus Dyar and Shannon. A, male: B, female;
C. pupa; D, eggs; E, larva (phantom larva); F. eversible pharyngeal sac extended
from the mouth. (After Herms. 1937.)
mouth; antennre extended downwards, simple, and with three to five apical
bristles that aid in securing food and in locomotion; labium with about 20 stout
hairs; a pair of fans of eight to nine hairs each; mandibles consist of four separate
chitinized dentides; maxillre fleshy. The large mouth also has a spacious eversible
pharyngeal sac or basket which functions as a crop for the selection of
food and the rejection of extraneous materials. The larvre have a pair of pigmented
air sacs in the thorax and also in abdominal segment VII which may
serve to regulate flotation and pressure. They move smoothly and rapidly
through the water or they may double up and dart after the larger living prey.